A hybrid vehicle which runs on the drive power of an engine and a motor is known. A motor in such a hybrid vehicle is operated by the electrical power of a battery. A large drive force is obtained by operating both the engine and the motor at the same time when, for example, the vehicle is accelerating. When the charge of the battery is low, the motor functions as a generator. The battery is charged by the motor being driven by the engine to generate electricity.
However when the vehicle is running on the drive force of both the engine and the motor, in consideration of operating conditions such as generation of electricity by the motor, speed change control by the transmission or the response of the engine, it is necessary to control the motor and the engine cooperatively so that the response and overall effect of vehicle operation is optimized.